Collector of dissolved metal from sea water having an amidoxime group and a hydrophilic group, a method for production thereof, a collecting cassette comprising laminated collectors, and a method for adsorbing and collecting dissolved metal from sea water by the cassette

Abstract

A collector is disclosed that is made of a polyolefin fiber having amidoxime groups and that is capable of efficient adsorptive recovery of useful metals such as uranium, vanadium, cobalt and titanium which are dissolved in small quantities in seawater. In the presence of a polymerizable monomer having a hydrophilic group, a polymerizable monomer having a cyano group is grafted to a polyolefin fiber by radiation-initiated graft polymerization to form both a hydrophilic group and a cyano group in the same graft side chains, and the cyano groups in the graft side chains are reacted with hydroxylamine to be converted to amidoxime groups, thereby producing a collector capable of recovering dissolved metals from seawater.

What is claimed is:  
     
         1 . A collector of dissolved metals from seawater that is made of a polyolefinic fiber having both an amidoxime group and a hydrophilic group in the same graft side chains.  
     
     
         2 . The collector according to  claim 1 , wherein the molar ratio of the amidoxime group to the hydrophilic group is in the range of 70:30 to 30:70.  
     
     
         3 . The collector according to  claim 1 , wherein the molar ratio of the amidoxime group to the hydrophilic group is in the range of 60:40 to 40:60.  
     
     
         4 . The collector according to  claim 1 , wherein the molar ratio of the amidoxime group to the hydrophilic group is 50:50.  
     
     
         5 . A process for producing a collector of dissolved metals from seawater which comprises the steps of grafting a polymerizable monomer having a cyano group onto a polyolefin fiber in the presence of a polymerizable monomer having a hydrophilic group and then reacting the cyano groups in the graft side chains with hydroxylamine to convert them to amidoxime groups, whereby both amidoxime and hydrophilic groups are introduced into the same graft side chains.  
     
     
         6 . A collector for adsorptive recovery of dissolved metals from seawater that is produced by grafting a monomer having a cyano group onto a substrate fiber in the form of either a nonwoven or woven cloth that is made of a polyolefinic fiber and converting the cyano groups in the resulting graft side chains to amidoxime groups.  
     
     
         7 . A collector for adsorptive recovery of dissolved metals from seawater that is produced by grafting a polymerizable monomer having a hydrophilic group onto a substrate fiber in the form of either a nonwoven or woven cloth that is made of a polyolefinic fiber, then grafting a monomer having a cyano group, and converting the cyano groups in the resulting graft side chains to amidoxime groups, thereby introducing both a hydrophilic group and an amidoxime group in different side chains.  
     
     
         8 . A collector for adsorptive recovery of dissolved metals from seawater that is produced by grafting a monomer having a cyano group onto a substrate fiber in the form of either a nonwoven or woven cloth that is made of a polyolefinic fiber in the presence of a polymerizable monomer having a hydrophilic group, and then converting the cyano groups in the resulting graft side chains to amidoxime groups, thereby introducing both a hydrophilic group and an amidoxime group in the same side chains.  
     
     
         9 . A collector for separation and recovery of dissolved metals from seawater that is produced by grafting a monomer having a cyano group onto a substrate fiber in the form of either a nonwoven or woven cloth that is made of a fiber of a core/sheath structure that has a polyolefinic fiber coated with a different polyolefin and converting the cyano groups in the resulting graft side chains to amidoxime groups.  
     
     
         10 . A collector for separation and recovery of dissolved metals from seawater that is produced by grafting a polymerizable monomer having a hydrophilic group onto a substrate fiber in the form of either a nonwoven or woven cloth that is made of a fiber of a core/sheath structure that has a polyolefinic fiber coated with a different polyolefin, then grafting a monomer having a cyano group, and converting the cyano groups in the resulting graft side chains to amidoxime groups, thereby introducing both a hydrophilic group and an amidoxime group in different side chains.  
     
     
         11 . A collector for adsorptive recovery of dissolved metals from seawater that is produced by grafting a monomer having a cyano group onto a substrate fiber in the form of either a nonwoven or woven cloth that is made of a fiber of a core/sheath structure that has a polyolefinic fiber coated with a different polyolefin in the presence of a polymerizable monomer having a hydrophilic group, and then converting the cyano groups in the resulting graft side chains to amidoxime groups, thereby introducing both a hydrophilic group and an amidoxime group in the same side chains.  
     
     
         12 . The collector according to any one of claims  6 - 11 , wherein the polymerizable monomer having a hydrophilic group is at least one member of the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, allyl alcohol, polyethylene glycol acrylate, polyethylene glycol methacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, N-vinylpyrrolidone, acrylamide and mixtures thereof.  
     
     
         13 . The collector according to any one of claims  6 - 11 , wherein the polymerizable monomer having a cyano group is at least one member of the group consisting of acrylonitrile, vinylidene cyanide, crotononitrile, metacrylonitrile, chloroacrylonitrile, 2-cyanomethyl acrylate, 2-cyanoethyl acrylate and mixtures thereof.  
     
     
         14 . A cassette of the collectors according to any one of claims  6 - 13  which are stacked and fixed at suitable spacings.  
     
     
         15 . A method for adsorptive recovery of dissolved metals from seawater, in which cages each containing the cassette according to  claim 14  are attached to a rope at given spacings and anchored in seawater.